1. Field of the Invention
This invention relates to an Asynchronous Transfer Mode (ATM) multiplexing process device and a method for processing an ATM multiplexing of a broadband integrated service digital network (B-ISDN, subscriber access apparatus. The broadband subscriber access apparatus constituting a broadband access network in the B-ISDN multiplexes the ATM (Asynchronous Transfer Mode) cells per line and per virtual connection input through the standard interface, abiding by the quality of service agreed to at the time of the connection establishment by granting an extra value in accordance with the buffer (FIFO) state used at each input terminal, the QOS (Quality of Service) class of the input service traffic following the connection, the differential threshold process according to this QOS class and the management viewpoint of the network operator.
2. Description of the Prior Art
The necessity for a subscriber access network is being raised and a subscriber access apparatus with the various topologies as the required device is being researched, in order to own the resources such as the bandwidth of the line jointly in an efficient way, manage the telecommunications network appropriately in accordance with the subscriber characteristics and control the capabilities of the multimedia service, the broadcasting and distribution service support, the multiple connection and the multiple-way communications efficiently when the service with the various traffic characteristics such as the audio, video and data service in B-ISDN is interfaced with the network.
The multiplexing process is essential to the access apparatus with the concentrated architecture in order to accommodate these complicated requirements and own the resources efficiently. This requires the designing of the ATM multiplexing process device equipped in the B-ISDN subscriber access apparatus of the STM-1 (Synchronous Transfer Mode-1) class which accommodates the service requirement of the subscriber and allows the operator to manage the network efficiently.
The design of the multiplexing process device is very important in the system design for the B-ISDN, because there are difficulties in basically providing the quality of service agreed to at the time the connection is established under the B-ISDN circumstances of the various transmission characteristics such as the variable bit rate and burstness. The performance of the multiplexing process device influences the performance of the entire telecommunications system as well as the performance of the subscriber access apparatus especially, though various kinds of ATM multiplexers using the statistical technique have been proposed currently.
FIG. 1A and 1B are a configuration diagram of the conventional ATM multiplexing process devices.
FIG. 1A shows an ATM multiplexing process device employing the scheduling algorithm of a polling method, which concentrates the ATM cells inputting through each input buffer at one output line sequentially with a use of a scheduler part by being equipped with multiple(N) input buffers, a scheduling controller and a scheduler part.
A connection state management part performs a function in sending connection establishment information instructing the operations following each connection to the scheduling controller after receiving its input from a signal process part, and performs a transfer of the buffer state information input from the scheduling controller to the signal process part.
This is a method of multiplexing while observing only the level of each input buffer regardless of the subscriber QOS requirements, which operates in a way to exclude the empty buffer sequentially from the scheduling order and pass the output order over to the next buffer. Therefore, there has been a problem with bandwidth being wasted.
FIG. 1B shows an ATM multiplexing process device employing the scheduling algorithm of a weighted round robin method, equipped with multiple (N) input buffers, a VPI/VCI (Virtual Path Identifier/Virtual Channel Identifier), a buffer of each VPI/VCI, the scheduler part, the scheduling controller, the connection state management part and the signal process part, which operates in a way to store the respective cell in the separate buffer according to the VPI/VCI which first of all, allocate the extra value in accordance with the relative ratio of the bandwidth agreed to for each VPI/VCI at the time of the connection establishment subsequently and grant the additional output opportunity as much as the extra value to the order sequentially operating.
Therefore, there has been a problem that only the bandwidth among the QOS parameters is considered, and not the cell loss ratio and the cell delay influencing the QOS enormously.